Petrillo in U.S. Pat. No. 4,168,267 discloses that various phosphinylakanoyl substituted prolines are useful as hypotensive agents due to their ability to inhibit the angiotensin converting enzyme.
Ondetti et al in U.S. Pat. No. 4,151,172 discloses that various phosphonoacyl prolines are useful as hypotensive agents due to their ability to inhibit the angiotensin converting enzyme.
Mercaptoacyl derivatives of proline and substituted prolines are known to be useful hypotensive agents due to their angiotensin converting enzyme inhibition activity. Ondetti et al in U.S. Pat. No. 4,105,776 disclose such compounds wherein the proline ring is unsubstituted or substituted by an alkyl or hydroxy group. Ondetti et al in U.S. Pat. No. 4,154,935 disclose such compounds wherein the proline ring is substituted with one or more halogens. Ondetti et al in U.K. Patent Application No. 2,028,327 disclose such compounds wherein the proline ring is substituted by various ethers and thioethers. Krapcho in U.S. Pat. No. 4,217,359 discloses such compounds wherein the proline ring has a carbamoyloxy substituent. Krapcho in U.K. Patent Application No. 2,039,478 discloses such compounds wherein the proline ring has a diether, dithioether, ketal or thioketal substituent in the 4-position, Krapcho in U.S. Pat. No. 4,316,905 discloses such compounds wherein the proline ring has a cycloakly, phenyl, or phenyl-lower alkylene substituent. Ondetti et al in U.S. Pat. No. 4,234,489 disclose such compounds wherein the proline has a keto substituent in the 5-position. Krapcho et al in U.S. Pat. No. 4,310,461 disclose such compounds wherein the proline has an imido, amido, or amino substituent in the 4-position. Iwao et al in U.K. Patent Application No. 2,027,025 disclose such compounds wherein the proline has an aromatic substituent in the 5-position.
Mercaptoacyl derivatives of 3,4-dehydroproline are disclosed as angiotensin converting enzyme inhibitors by Ondetti in U.S. Pat. No. 4,129,566. Mercaptoacyl derivatives of thiazolidinecarboxylic acid and substituted thiazolidinecarboxylic acid are disclosed as angiotensin converting enzyme inhibitors by Ondetti in U.S. Pat. No. 4,192,878 and by Yoshitomo Pharmaceutical Ind. in Belgian Pat. No. 868,532.